Artificial birefringence introduced by porosity in GaP

Abstract

Porosity-induced birefringence in a GaP membrane is studied using a method based on the analysis of beats in unpolarized and polarized transmittance spectra as well as in angular dependence of optical spectra. Birefringence as high as ne − no = 0.25 was measured in a porous GaP membrane with the degree of porosity close to 40%. The measured values of ne and no are compared with those calculated in the frame of effective medium theory for a GaP membrane with appropriate morphology.